TWI553430B - A focusing leveling device - Google Patents

Description

Focusing leveling device

The present invention relates to the field of lithography, and more particularly to an autofocus device with a refractive unit for a lithography machine.

Current projection lithography systems typically include an autofocus grading system for accurately detecting the surface height and tilt of the object being measured. FIG. 1 is a schematic diagram of a focus adjustment leveling system of a conventional projection lithography machine. As shown in FIG. 1, the projection aligner leveling system includes a projection objective 19 and measurement optical paths distributed on both sides of the optical axis of the projection objective 19. The measuring optical path includes a lighting unit, a projection unit, a detecting unit, and a relay unit that are sequentially arranged along the optical path. The illumination unit is composed of an illumination source 1, an illumination mirror 2 and an optical fiber (not shown); the emitted light of the light source is collected by the illumination mirror 2, and then transmitted by the optical fiber to the projection unit to provide an illumination source for the entire measurement device. The projection unit is composed of a projection slit 3, a pre-projection group lens group 4, a mirror group 5, and a post-projection lens group 6. The light emitted from the illumination unit passes through the projection slit and then passes through the pre-projection lens group 4 and reflects. The mirror group 5 and the post-projection group lens group 6 form a measurement spot in the current exposure region of the surface of the object 7 to be measured. The detecting unit is composed of the pre-detecting group lens group 8, the mirror group 9, and the post-detecting group lens group 10; after passing through the detecting unit, it enters the relay unit. The relay unit is composed of a relay mirror 11, a relay lens group 12, a detector 13, a focus controller 14, and an arithmetic unit 15, and the spot passing through the relay unit is received by the detector 13 to form a test object. Surface position and intensity information for tilt information.

The technical solution of an embodiment of US Pat. No. 5,414,515 is to provide A single optical path is generated to generate a plurality of measurement spots, and corresponding CCDs are used under the requirement of satisfying a certain measurement field of view. The disadvantages of the above solutions are: the number of CCDs used is large, and the CCD corresponding image acquisition card There are also more cables and higher costs. In addition, the large number of CCDs will cause space constraints to be tighter, and it is not possible to better increase the freedom of space constraints for the whole machine.

Chinese patent CN101710291 shows a parallel light refraction list The solar device of the element lens is different from the solution of the present invention in that there is a difference in application. The technical solution of CN101710291 focuses on the energy gathering of the light beam, and there is no image quality requirement, and the present invention is used for the adjustment of the imaging position. And there are requirements for image resolution, distortion, depth of focus and other image quality, so there is an essential difference between the two.

The object of the present invention is to propose a new structure of a leveling and focusing subsystem of a projection lithography machine: by introducing a refracting unit in the optical path, a large field of view can be satisfied by using only a single optical path and a single linear array CCD. The system requirements for multipoint measurement, and overall reduced costs, reducing space occupancy.

A focusing leveling device according to the present invention includes: an illumination source for emitting a light beam, and an illumination mirror group, a projection mirror group, an object to be measured, a detection mirror group, and a refractive index which are sequentially arranged along a transmission path of the light beam a unit, a relay mirror group and a photodetector, wherein the photodetector is configured to convert a light beam that is emitted from the relay lens group and carries information related to the height and inclination of the surface of the object to be measured into an electrical signal, and then transmit the light beam to the electrical signal An arithmetic unit and a focus leveling controller, wherein the arithmetic unit generates a control signal according to the received electrical signal and supplies the control signal to the focus leveling controller, so that the focus leveling controller controls the hosted object to be measured One workpiece table The height and inclination of the measured object are adjusted; the projection mirror group includes a projection slit, and the projection slit has a plurality of marks not in the same straight line, so that the light beam emitted by the illumination source sequentially passes through the illumination mirror group and the projection a plurality of sub-beams not corresponding to the plurality of marks are generated by the mirror group, the object to be measured, and the detector group, and the refraction unit is configured to generate the plurality of sub-beams on the same line after passing through the refraction unit Multiple spots.

Preferably, the projection slit has at least three marks that are not in the same straight line.

Preferably, the projection mirror set further includes a double jaw group having two turns, and the projection slit is sandwiched between the two turns of the pair of turns.

Preferably, the refracting unit includes a refractive mirror group, a refractive lens group, and a refractive iridium group.

Preferably, the refractive mirror group is composed of n-1 refractive mirrors, and the refractive lens group is composed of n refractive lenses, and the refractive hologram group is composed of n-1 refractive indexes, wherein n The number of marks on the slit that are not in the same line.

Preferably, the refracting unit further includes a parallel plate, and the intermediate sub-beams of the plurality of sub-beams incident on the refracting unit are incident on the parallel slab through the corresponding refracting lens, and the other sub-beams sequentially pass through the corresponding refracting mirror and the refracting lens. And the refracting ridge is incident on the relay lens group together with the intermediate sub-beam.

Preferably, the photodetector is a single linear array CCD.

Preferably, the refracting unit comprises two wedge plates, and the two wedge plates are placed in a long inclined manner.

Preferably, the middle and lower portions of the first of the two wedge plates are a first through hole is opened, and the position of the first through hole corresponds to a position where the sub-beams located in the middle and below of the plurality of sub-beams incident on the refractive unit are incident on the first wedge plate, and the first of the two wedge plates The middle portion and the upper portion of the two wedge plates are provided with a second through hole, and the position of the second through hole corresponds to a position at which the sub-beams located in the middle and above of the plurality of sub-beams incident on the refractive unit are incident on the second wedge plate.

Preferably, the refracting unit further includes a parallel plate and a placement position thereof. The intermediate sub-beams of the plurality of sub-beams are first passed through the first and second through holes corresponding to the first wedge plate and the middle of the second wedge plate, and then incident on the parallel plate.

Different from the two common structures of the existing technology: the first one, the design is more The optical path generates a plurality of measurement spots, and correspondingly multiple linear array CCDs are required under a larger measurement field of view; second, a single optical path is designed to generate a plurality of measurement spots, and in a larger measurement field of view Under the demand, a single area array CCD is used. The invention proposes a new structure in the leveling and focusing subsystem of the projection lithography machine: by introducing a refraction unit in the optical path, the focusing device of the invention only needs to adopt a single optical path and a single by using the refraction unit. The linear array CCD can meet the system requirements of large field of view and multi-point measurement, which reduces the overall cost and reduces the space occupancy.

The advantages and spirit of the present invention will be further understood from the following detailed description of the invention.

1, 101, 201, 301‧‧‧ illumination source

2, 102, 202, 302‧‧‧ lighting mirror set

3, 103, 203, 303‧‧ ‧ projection slit

4, 105, 205, 305 ‧ ‧ front projection lens group

5, 9‧‧‧Mirror group

6, 207, 307 ‧ ‧ projection group lens group

7, 109, 209, 309‧‧‧ Measured objects

8, 111, 211, 311‧‧ ‧ pre-detection group lens group

10, 113, 213, 313‧‧ ‧ post-detection group lens group

11‧‧‧Relay mirror

12, 116, 219, 317‧‧ ‧ relay lens group

13‧‧‧Detector

14, 118, 221, 319‧ ‧ focus controller

15, 119, 222, 320‧‧‧ arithmetic unit

104, 204, 304‧ ‧ 稜鏡 double 稜鏡 group

106, 206, 306‧‧ ‧ projection aperture

108, 208, 308‧‧‧ projection mirror

110, 210, 310‧‧ ‧ pre-detection group mirror

112, 212, 312‧ ‧ detection aperture

114, 214, 314‧‧ ‧ post-detection group mirror

115‧‧‧Refractive unit

117, 220, 318‧‧‧ linear array CCD

120,223,321‧‧‧Control workpiece table

215 (215a-215h)‧‧‧Refractive unit mirror group

216 (216a-216e) ‧ ‧ refracting unit lens unit

217, 316‧‧‧ parallel plates

218 (218a-218d) ‧ ‧ Refracting unit 稜鏡

315‧‧‧Wedge plate group

315a, 315b‧‧‧ wedge

A, B, C, D, E‧‧‧ mark location

Figure 1 shows the schematic diagram of the focus adjustment system of the projection lithography machine.

2 is a schematic diagram of a focus leveling system with a refractive unit according to the present invention.

FIG. 3 is a schematic diagram of a focusing and leveling device with a mirror group refraction unit according to the present invention.

Figure 4 is a partial view of the mirror unit of the mirror assembly of the present invention.

FIG. 5A is a schematic view showing a projection slit according to an embodiment of the present invention.

FIG. 5B is a view showing the position of a spot on the image plane before the light beam passes through the refractive unit according to an embodiment of the present invention.

FIG. 5C shows the spot position on the image surface of the light beam after passing through the refractive unit according to an embodiment of the invention.

FIG. 6A is a schematic view showing a projection slit according to another embodiment of the present invention.

Fig. 6B is a view showing the position of a spot on the image plane before the light beam passes through the refractive unit according to another embodiment of the present invention.

6C is a view showing a spot position on an image surface of a light beam passing through a refractive unit according to another embodiment of the present invention.

Fig. 7 is a view showing the position of a spot on the line CCD of Figs. 5C and 6C.

FIG. 8 is a schematic diagram of a focusing and leveling device with a wedge plate group refraction unit according to the present invention.

Fig. 9 is a partial view showing the refractive unit of the wedge plate group of the present invention.

Specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[First Embodiment]

FIG. 2 shows a focusing and leveling device with a refractive unit of a projection lithography machine according to the present invention. As shown, the apparatus includes an illumination source 101, an illumination lens set 102, a projection slit 103, a double eye group 104, a pre-projection lens group 105, a projection aperture 106, a post-projection lens group 107, and a projection mirror 108. , the object to be measured 109, the pre-detection group mirror 110, Pre-detection group lens group 111, detection aperture 112, post-detection group lens group 113, post-detection group mirror 114, refraction unit 115, relay lens group 116, line array CCD 117, focus controller 118, arithmetic unit 119; The light beam emitted from the illumination source 101 passes through the illumination mirror group 102 and is projected onto the projection slit 103. The projection slit is sandwiched between the two turns of the double-twist group 104, and the light beam emitted by the double-twist group 104 passes through the projection. After the group lens group 105, the projection aperture 106 and the post-projection group lens group 107 are reflected by the projection mirror 108 onto the object to be measured 109, after being reflected by the object to be measured 109, it reaches the pre-detection group mirror 110, and then the pre-detection group The mirror 110 is reflected to the pre-detection group lens group 111, the detection aperture 112, and the post-detection group lens group 113. After reaching the post-detection group mirror 114, it is reflected, and after passing through the refraction unit 115, the spot is imaged in the same line of view. After passing through the relay lens group 116, it is received by the line array CCD 117, and the line array CCD 117 obtains the height information and the tilt information of the surface of the object related thereto by information photoelectric conversion, and is sent to the arithmetic unit 119 by the focus controller 118. Braking the workpiece table 120, so that the height and tilt of the object 109 is adjusted accordingly.

3 is a projection lithography machine according to a first embodiment of the present invention Focal bisector system A schematic diagram of a focusing and leveling device with a refractive unit for accurately and efficiently measuring the surface position of a silicon wafer (silicon wafer; germanium). As shown, the apparatus includes an illumination source 201, an illumination mirror set 202, a projection slit 203, a double eye group 204, a pre-projection lens group 205, a projection aperture 206, a post-projection lens group 207, and a projection mirror 208. The measured object 209, the pre-detection group mirror 210, the pre-detection group lens group 211, the detection aperture 212, the post-detection group lens group 213, the post-detection group mirror 214, the refractive unit mirror group 215, and the refractive unit lens group 216 The parallel plate 217, the refractive unit unit group 218, the relay lens group 219, the line array CCD 220, the focus controller 221, and the arithmetic unit 222. The light beam emitted from the illumination source 201 passes through the illumination mirror set 202 and is projected onto the projection slit 203. The projection slit is sandwiched between the double-twist group 204, and the light beam emitted by the double-twist group 204 passes through the front lens group 205, the projection aperture 206, and the rear lens group 207, and is reflected by the projection mirror 208. The measured object 209 is reflected by the measured object 209 and reaches the pre-detection group mirror 210, and then reflected by the pre-detection group mirror 210 to the pre-detection group lens group 211, the detection aperture 212, and the post-detection group lens group 213. After detecting, the group mirror 214 is reflected and respectively reflected to the refractive unit mirror group 215 (215a-215h), and the incident light unit lens group 216 (216a-216e) is passed. The intermediate beam passes through the parallel plate 217, and the edge beams pass through the refractive unit edge. Mirror group 218 (218a-218d), wherein mark B corresponds to 215a, 215b, 216a and 218a, mark A corresponds to 215c, 215d, 216b and 218b, mark D corresponds to 215e, 215f, 216c and 218c, and mark E corresponds to 215g, 215h, 216d and 218d, together with the intermediate beam, pass through the relay lens group 219, and are received by the line array CCD220, and the line array CCD220 obtains the height information and tilt information of the surface of the object related thereto by information photoelectric conversion, and is controlled by focusing. 221 After to the arithmetic unit 222, control of the workpiece stage 223, so that the height and tilt of the object 209 to be adjusted. In the present embodiment, although the figure is shown and described as the light beam is incident in the horizontal direction, in practice, it is not limited to being incident in the horizontal direction, and the refractive unit mirror group 215 is used to separate the respective light beams, and the respective light beams pass through. The refractive unit lens group 216 is imaged, and is further folded by the refractive unit unit group 218 onto the relay lens group 219, and finally linearly arranged on the line array CCD220. Figure 4 is a partial view of the mirror refractor unit. As shown in the figure, the refracting unit includes a refracting unit mirror group 215, a refracting unit lens group 216, a parallel flat plate 217, and a refracting unit 稜鏡 group 218; the light beam is reflected by the refracting unit mirror group 215, and is incident on the refracting unit lens group. 216, wherein the middle one beam passes through the parallel flat plate 217, and the four beams of the edge pass through the refractive unit 稜鏡 group 218 and then pass through the relay lens group 219 together with the intermediate beam, and are received by the line CCD 220.

5A and 6A are schematic views showing the structure of two kinds of projection slits. The projection slit is obliquely placed in the middle of the double jaw assembly 204, and the marked positions on the slit are as shown in Figs. A, B, C, D, and E. 5B and FIG. 6B respectively correspond to the light beam position corresponding to the two kinds of projection slit structures shown in FIG. 5A and FIG. 6A, and the spot positions on the image surface are A ' , B ' , C ' , D ' , E '. The spot position is spatially distributed. 5C and FIG. 6C respectively correspond to the light-receiving units corresponding to the two kinds of projection slit structures shown in FIG. 5A and FIG. 6A, and the position of the spot on the image surface is A " , B " , C " , D " , E " , The spot is arranged in a straight line; finally, it passes through the relay lens group 219 and is received by the line CCD 220, thereby functioning to convert the spot distribution from the field of view distribution to the line field distribution.

Fig. 7 is a view showing the position of a spot on the line CCD of Figs. 5C and 6C. Finally, the imaging spot on the CCD is A''' , B''' , C''' , D''' , E''' in a straight line arrangement.

[Second embodiment]

8 is a schematic diagram of a focus leveling device with a wedge plate group refraction unit for a focus grading system of a projection lithography machine according to a second embodiment of the present invention, for accurately and efficiently measuring a bismuth wafer ( Silicon wafer; ruthenium) surface position. As shown, the above apparatus includes an illumination source 301, an illumination mirror 302, a projection slit 303, a double eye group 304, a pre-projection lens group 305, a projection aperture 306, a post-projection lens group 307, and a projection mirror 308. The measured object 309, the pre-detection group mirror 310, the pre-detection group lens group 311, the detection aperture 312, the post-detection group lens group 313, the post-detection group mirror 314, the refractive unit wedge plate group 315, the parallel plate 316, and the middle Following the lens group 317, the line CCD 318, the focus controller 319, and the arithmetic unit 320. The light beam emitted from the illumination source 301 passes through the illumination mirror 302 and is projected onto the projection slit 303, and the projection slit is sandwiched between the double-twist group 304. The beam emitted by the double-twist group 304 passes through the pre-projection lens group 305, the projection aperture 306, and the post-projection lens group 307, and is reflected by the projection mirror 308 onto the object to be measured 309, and is reflected by the object 309 to be detected. The front group mirror 310 is further reflected by the pre-detection group mirror 310 to the pre-detection group lens group 311, the detection aperture 312 and the post-detection group lens group 313, and then reflected by the detected group mirror 314 to the refractive unit wedge plate group. After 315, the intermediate beam passes through the parallel plate 316, and the edge beam passes through the wedge plate group 315 and passes through the intermediate beam, passes through the relay lens group 317, and is received by the line array CCD 318. The line array CCD 318 is obtained through information photoelectric conversion. The height information and the tilt information of the surface of the object are sent to the arithmetic unit 320 by the focus controller 319, and the workpiece stage 321 is controlled to adjust the height and tilt of the object 309 to be measured.

Figure 9 shows the schematic diagram of the wedge plate group refraction unit. As shown in the figure, the refractive unit comprises a parallel flat plate 316 and a refractive unit wedge plate group 315. The wedge plate group 315 is formed by two wedge plate wedge angles; the light beam is reflected by the detected group mirror 314, and then passes through a pair. A special wedge set 315 is imaged on the same image plane. Wherein, the wedge angle direction of 315a is the same direction as the marks B and D (ie, the sharp angle of the wedge angle of 315a faces upward), and the wedge angle direction of 315b is the same direction as the marks A and E (ie, the sharp angle of the wedge angle of 315b faces downward), The angle of change satisfies the formula: δ = α ( n -1), where n is the refractive index of the wedge plate, α is the angle of the wedge plate less than 5 degrees, and the light is incident as perpendicular or nearly perpendicular to the wedge plate and is terminated by the relay lens group 317 is finally imaged on the line CCD 318, wherein the lower two beams are incident on the corresponding position of the first wedge plate 315a to dig two small holes, and the upper two beams are deflected by 315a and then incident on the second wedge plate 315b. Two small holes are dug at the corresponding positions, and the intermediate beam is incident on the corresponding positions of the wedge plates 315a and 315b, and each of the small holes is dug, and the holes are all through holes, so that the light beam passing through the through holes is not deflected. And a parallel plate 316 is added on the intermediate optical path to compensate for the optical path difference, and the multiple beams are refracted by the wedge plate group 315, so that the spot can be arranged on the image surface after the wedge plate group 315 is distributed from the surface field of view. After being converted into a line field of view, and after passing through the relay lens group 317, it is finally received by the line array CCD 318.

The description of the present invention is only a preferred embodiment of the present invention, and the above embodiments are merely illustrative of the technical solutions of the present invention and are not intended to limit the present invention. Any technical solution that can be obtained by a person skilled in the art according to the concept of the present invention by logic analysis, reasoning or limited experimentation should be within the scope of the present invention.

201‧‧‧Light source

202‧‧‧Lighting mirror

203‧‧‧Projection slit

204‧‧‧Double Group

205‧‧‧Pre-projection lens group

206‧‧‧Projection aperture

207‧‧‧Projected rear lens group

208‧‧‧projection mirror

209‧‧‧Measured objects

210‧‧‧Pre-detection group mirror

211‧‧‧Pre-detection group lens group

212‧‧‧Detection aperture

213‧‧‧Detecting group lens group

214‧‧‧post-detection group mirror

215a-215h‧‧‧Refractive unit mirror group

216a-216e‧‧‧Refractive unit lens unit

217‧‧‧ parallel plates

218a-218d‧‧‧Refractive unit

219‧‧‧Relay lens group

220‧‧‧Line CCD

221‧‧‧ focus controller

222‧‧‧ arithmetic unit

223‧‧‧Control workpiece table

Claims (10)

A focusing and leveling device comprising: an illumination source for emitting a light beam, and an illumination mirror group, a projection mirror group, an object to be measured, a detection mirror group, a refractive index unit, and a relay arranged in sequence along a transmission path of the light beam a mirror group and a photodetector, wherein the photodetector is configured to convert a light beam that is emitted from the relay lens group and that carries information related to the height and inclination of the surface of the object to be measured into an electrical signal, and then transmit the light beam to the arithmetic unit and adjust a focus leveling controller, wherein the arithmetic unit generates a control signal according to the received electrical signal to provide the focus leveling controller, so that the focus leveling controller controls a workpiece stage carrying the object to be measured Adjusting the height and inclination of the object to be measured, the photodetector obtains the height information and the tilt information of the surface of the object to be tested related to the photoelectric detector by information photoelectric conversion, and sends the information to the arithmetic unit by the focus leveling controller After that, the workpiece table is controlled to adjust the height and inclination of the object to be measured correspondingly; The mirror group includes a projection slit, and the projection slit has a plurality of marks not in the same straight line, so that the light beam emitted by the illumination source sequentially passes through the illumination mirror group, the projection mirror group, the measured object and the detection mirror group, and generates the above The plurality of markers correspond to the plurality of sub-beams not in the same straight line, and the refraction unit is configured to generate the plurality of spots on the same straight line after the plurality of sub-beams pass through the refraction unit. The focusing leveling device of claim 1, wherein the projection slit has at least three marks that are not in the same straight line. The focusing and leveling device of claim 1, wherein the projection mirror group further comprises a double cymbal group having two cymbals, and the projection slit is sandwiched between two cymbals of the pair of cymbals . The focusing and leveling device of claim 1, wherein the refractive unit comprises a refractive mirror group, a refractive lens group and a refractive iridium group. The focusing and leveling device of claim 4, wherein the refractive mirror group is composed of n-1 refractive mirrors, and the refractive lens group is composed of n refractive lenses, and the refractive index group is composed of N-1 blocks of refraction ,, where n is the number of marks on the projection slit that are not in the same line. The focusing and leveling device of claim 5, wherein the refracting unit further comprises a parallel plate, and the intermediate sub-beams of the plurality of sub-beams incident on the refracting unit are incident on the parallel plate through the corresponding refracting lens, and the other sub- The light beams are sequentially passed through the corresponding refractive mirror, the refractive lens, and the refracting ridge, and then incident on the relay lens group together with the intermediate sub-beam. The focusing leveling device of claim 1, wherein the photodetector is a single linear array CCD. The focusing and leveling device of claim 1, wherein the refracting unit comprises two wedge plates, and the two wedge plates are placed in a long inclined manner. The focusing and leveling device of claim 8, wherein a first through hole is formed in a middle portion and a lower portion of the first wedge plate of the two wedge plates, and the position of the first through hole is incident to the refractive index a position in which the sub-beams in the middle and the lower part of the plurality of sub-beams are incident on the first wedge plate, and a second through hole is formed in the middle and the upper part of the second wedge plate of the two wedge plates, the second The position of the through hole corresponds to a position at which the sub-beams located in the middle and above of the plurality of sub-beams incident to the refractive unit are incident on the second wedge plate. The focusing leveling device of claim 9, wherein the refracting unit further comprises a parallel plate disposed at a position such that the intermediate sub-beams of the plurality of sub-beams pass through the first wedge plate and the second wedge plate first. The first and second pass corresponding to the middle The holes are then incident on the parallel plates.